This invention relates generally to vertical turbine pumps and more particularly to vertical turbine pumps having a low number of appropriate thick diffuser vanes and minimal bowl diameter and weight for pumping both single phase and multiphase fluids, more particularly fluids containing fibrous materials and other solids.
The traditional design of a bowl for both a wet pit and dry pit solids-handling vertical turbine pump with few vanes, in order to allow passage of solid particles with relatively large diameter, results in a bowl with large masses of metal between the vanes which contribute nothing to the function of the pump. In addition, transition passage area control, required for hydraulic parameter optimization, leads to very large thicknesses for most of the extent of the vanes, which makes casting of such bowls very difficult due to radical changes of section thickness and mass which makes uniform cooling very difficult to achieve and often causes cracking. Pump bowls of traditional design have each hydraulic passage near to the next and separated from the next by a vane whose thickness is dictated by castability constraints and pattern and core requirements. Therefore, the hydraulic passages are overly constrained and negatively affected. This results in poor diffusion and strong vortical turbulent flows which lower the efficiency of the pump and increase the risk of poor reliability due to high vibration. Such pumps, in spite of their less than optimal efficiency, are very heavy and, because of the casting difficulties described, unnecessarily expensive.
The foregoing illustrates limitations known to exist in present bowls for turbine pumps, and it would be advantageous to provide an alternative directed to overcoming one or more of those limitations. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.